Swing mechanism for backhoes



July 1, 1969 F w.. NOLLER ETAL SWING MECHANISM FOR BACKHOES Sheet Filed March 18. 1968 INVENTORS. H250 14 Mum 2 1 GZOAGf mam/610 B dfAAZfl-Z-SM/TH A7TOAWB6.

84 as L3 July 1, 1969 v F. w. NOLLER ET AL 3,452,882

SWING MECHANISM FOR BACKHOES Filed March 18, 1968 Sheet 2 o! 2 1-278 515 58 48 I mfi] LII INVENTORS. FREQ W. A/OZZf/i GfO/PGZ' W FM 61f) JERALD T SM/TH M /JAM United States Patent US. Cl. 212-66 8 Claims ABSTRACT OF THE DISCLOSURE A backhoe swing mechanism including a mast frame pivotally mounted on a support for side to side swinging movement. The mast frame is actuated about its pivotal connection with the support by a pair of hydraulic rams, each of which is connected through a lever with the mast frame. Each lever in turn is fulcrumed on one end of a link, the other end of the link being pivotally connected with the support. As one of the rams extends, its lever pushes the mast frame about its pivotal axis, and the other ram retracts to cause its lever to pull the mast frame about the pivotal axis.

This invention relates generally to mechanism for turning booms, cranes, and the like of material handling equipment, and is particularly concerned with a swing mechanism for material handling apparatus of the type commonly referred to as backhoes.

Presently available swing mechanisms which do not depend upon gears and turntables are frequently incapable of providing equal or adequate power at the end portions of arcuate travel of the boom. Moreover, the linkage constructions have heretofore tended to be undesirably bulky and complex and subject to frequent servicing problems due to wear.

In accordance with the present invention, a backhoe boom or mast is actuated about its pivotal connection with the backhoe support by a pair of rams connected with the boom frame by a lever. The lever is fulcrumed on one end of a link, the other end of the link being pivoted to the backhoe support to that the lever is on a moving fulcrum and is pivotally connected with the boom support at a point spaced from its pivotal axis. As one of the rams extends, its lever pushes the mast frame to rotate about its pivotal axis and the other ram simultaneously retracts to cause its lever to pull the boom frame about its pivotal axis. The mast frame can be rotated through an arc of 180 degrees with substantially uniform torque.

The objects, advantages and features of the invention will become apparent from the following description taken in connection with the accompanying drawings in which:

FIG. 1 is an elevational view of a tractor mounted backhoe embodying the invention;

FIG. 2 is a view taken on line 2-2 of FIG. 1;

FIG. 3 is a sectional view taken on line 33 of FIG. 2;

FIG. 4 is a view similar to FIG. 2 with the mast frame in an alternate position; and

FIG. 5 is a perspective view of the force transmitting linkage for actuating the mast frame about its pivotal axis.

In FIG. 1, reference numeral 2 collectively designates a backhoe support mounted on a tractor 4 having rear wheels 6, a seat 8, and a control console having handles for manipulating the hydraulic controls of the backhoe assembly. Mounted on the support is a backhoe boom assembly 12.

The backhoe support has a rear wall 14 (FIGS. 2 and 4) having side portions 16 each of which is formed with an opening 18. Projecting rearwardly from the rear wall 3,452,882 Patented July 1, 1969 14 is a horizontal upper support arm 20 and a lower support arm 22 (FIG. 1). Extending vertically between the spaced support arms 20 and 22 is a tubular post 24.

Pivotally mounted on arms 20 and 22 is a mast frame 26 having a lower mast frame arm 28 and an upper mast frame arm 30 which are respectively pivotally connected with support arms 22 and 20 about a swing axis 32. The lower support arm 22 is pivotally connected with mast frame 26 about axis 32 by a pin 34 (FIG. 2). Mast frame 26 is formed with a pair of horizontally spaced rearwardly projecting ears or lugs 36 on which the boom or mast 40 of boom assembly 12 is pivotally connected by a pin 38 in a conventional manner. The central portion 42 of mast frame 26 overlies the lower support arm 22 as shown in FIG. 1, and extends beneath the upper support arm 20.

Mast frame 26 is actuated about pivot axis 32 by a pair of hydraulic rams 44 and 46. Ram 44 includes a cylinder 48 pivotally supported at one end on the boom support at a location not shown, and a piston 50 which projects through opening 18. Ram 46 includes a cylinder 52 pivotally supported on the backhoe support at a location not shown and a piston 54 which projects through opening 18. Piston 50 of ram 44 is pivotally connected by a pin 58 to one end of a lever 56, the other end of which is pivotally connected by a pin 60 to a bracket 62 carried on the lower side of mast frame 26 (FIG. 1). Pin 60 is spaced from the pivot axis 32 as indicated more clearly in FIGS. 2 and 4. Pin 60 is received between the upper and lower arms 64 and 66, respectively, of bracket 62 (FIGS. 1 and 3).

Piston 54 is pivotally connected by a pin 70 with one end of a lever 68, the other end of which is also pivotally supported on pin 60. Projecting from the central portion of rear wall 14 beneath the lower support arm22 is a bracket 72 having a plurality (in this case 4) of rearwardly projecting, vertically spaced arms 74. A pair of links 76 are pivotally connected at one end by a pin to bracket arms 74, and have their other ends pivotally connected by a pin 78 to lever 56 substantially at its midpoint between pins 58 and 60. A similar pair of links 82 are supported at one end between arms 74 on pin 80 and at their other ends by pin 84 to lever 68 intermediate its ends. Consequently, pivot pin 78 provides a moving fulcrum for lever 56, and pivot pin 84 provides a moving fulcrum for lever 68.

In FIG. 2, the mast frame 26 is shown in its center or straight ahead position relative to the backhoe support in which pistons 50 and 54 are extended an equal amount from their respective cylinders 48 and 52. To turn mast frame 26 in a clockwise direction about axis 32, ram 44 is extended and ram 46 is correspondingly retracted. With reference to FIG. 4, as piston 50 extends from cylinder 48, link 76 rotates in a clockwise direction about the axis of pivot pin 80, and during the movement of link 76, lever 56 rotates in a clockwise direction about the moving fulcrum pin 78 which in turn causes mast frame 26 to pivot in a clockwise direction about pivot axis 32. The motion of lever 56 is transmitted to mast frame 26 through pin 60 which may rotate about the axis 32 through an arc of degrees from the position shown in FIG. 2 to that shown in FIG. 4. As ram 44 extends to the position shown in FIG. 4, the ram 46 contracts a corresponding amount to pull pin 60 in a clockwise direction about the pivot axis 32 which movement correspondingly causes link 82 to rotate in a clockwise direction about pin 80. Lever 68 rotates about the moving fulcrum pin 84 as ram 46 is retracted from the position shown in FIG. 2 to that shown in FIG. 4.

In the illustrated embodiment, the lengths of levers '56 and 68 are approximately four times the distance between the axes of pins 34 and 60, and are approximately twice 3 the length of links 76 and 82. The distance between pins 80 and 34 are preferably in the range of one to two times the distance between pins 34 and 60. As a result, the amount of force required is substantially uniform throughout the movement of the mast frame about an arc of 180 degrees relative to pivot axis 32.

While a specific example of the invention has been illustrated and described, it should be understood that the invention is not limited to the exact construction shown, but that various alterations and modifications in the construction and arrangement of parts, all falling within the scope and spirit of the invention, will be apparent to those skilled in the art.

We claim:

1. Material handling apparatus comprising: a support; a mast frame mounted on the support for side to side swinging movement about an upright swing axis; a pair of links each having one end pivotally connected to the support; a pair of levers, pivotally mounted intermediate their ends on respective ones of said links; a pair of extensible and retractible power elements mounted on the support; and means pivotally connecting one end of each of said levers with the mast frame, and the other end with respective ones of the power elements on opposite sides of the swing axis so that opposed extension and retraction of the power elements with respect to each other causes the mast frame to rotate about the swing axis with respect to the support.

2. Material handling apparatus as claimed in claim 1 wherein said one end of said levers are coaxially connected to the mast frame on an axis spaced from the swing axis.

3. Material handling apparatus as claimed in claim 2 wherein said one end of said links are coaxially connected with the support on an axis spaced from the swing axis.

4. Material handling apparatus as claimed in claim 3 wherein said power elements each comprise a hydraulic ram, the piston of which has its end pivotally connected with said other end of the associated lever.

5. Material handling apparatus as claimed in claim 1 wherein said support includes a pair of vertically spaced upper and lower support arms and said mast frame having a pair of upper and lower mast frame arms respectively pivotally connected with said upper and lower support arms on said swing axis.

6. Material handling apparatus as claimed in claim 5 wherein said support includes a rear wall and a bracket beneath the lower support arm; said links being pivotally connected to said bracket.

7. Material handling apparatus as claimed in claim 6 further including a bracket formed on the mast frame beneath the lower mast frame arm, said one end of said levers being pivotally connected with said last named bracket.

8. Material handling apparatus as claimed in claim 7 wherein said links are pivotally connected to the bracket on said support on an axis spaced from the swing axis, and said levers are pivotally connected with the bracket on the mast frame on an axis spaced from the swing axis.

References Cited UNITED STATES PATENTS 3,057,494 10/1962 Holopainen et a1. 2l4--138 3,097,750 7/1963 Stummer 212-66 3,395,812 8/ 1968 Arnold 212-66 HUGO O. SCHULZ, Primary Examiner.

US. Cl. X.R. 2l4--138, 151 

